The period 1550-1850 is well-known as the Little Ice Age in Europe. The purpose of this paper is to describe the summer climate of Edo in the early nineteenth century. For that purpose, the rainfall was estimated using a historical weather record. The daily weather record for Edo is available from “Hirosaki Hancho Edo Diary, ” a document of the feudal Tsugaru Clan. This study covers the summer months, June, July, and August, in the 1830s and 1840s. First, the summer days in the diary were sorted into four rainfall types according to the weather which was recorded in the diary: R1: heavy rain, R2: rain all day, R3: thunderstorm, R4: rainy days not included in the other three categories. Days with no rainfall were sorted as type N. Each of these rainfall types is given a class value which indicates the hypothetical daily precipitation. The hypothetical daily precipitation amounts were obtained by analyzing the distribution of recent observed daily precipitation. Last, the pre-cipitation of Edo was evaluated relative to each type of rainfall. Precipitation was estimated by substituting the class value. The results of this study are summarized as follows. Summers in Edo are considered to have been wetter than now. It often rained heavily in July and August. The difference is particularly remarkable in August. Summer precipitation in the 1830s and 1840s is estimated to have been 1.2-1.5 times that of today.